Method for manufacturing magnetic head device

ABSTRACT

A method for manufacturing a magnetic head device that includes a soft magnetic layer includes the steps of forming a plating base layer in the soft magnetic layer through sputtering, and applying, during the forming step, a magnetic field in a direction parallel to an orientation fringe of a wafer in which the magnetic head device is formed.

This application claims the right of foreign priority under 35 U.S.C.§119 based on Japanese Patent Application No. 2006-246633, filed on Sep.12, 2006, which is hereby incorporated by reference herein in itsentirety as if fully set forth herein.

BACKGROUND OF THE INVENTION

The present invention relates generally to a magnetic head devicemanufacturing method, and more particularly to a method formanufacturing a magnetic head device including a soft magnetic layer,such as a shield layer. The present invention is suitable, for example,for a read head having a magnetoresistive device used for a hard discdrive (“HDD”).

Along with the recent widespread Internet, a magnetic disc drive thatrecords a large amount of information including still and motionpictures has been increasingly demanded. When the surface recordingdensity is increased so as to meet the large-capacity demand, the 1-bitarea as a minimum unit of the magnetically recorded information on therecording medium reduces, and the signal magnetic field from therecording medium becomes weaker. In order to read this weak signalmagnetic field, a small and sensitive read head is needed.

For this read head, a read head having a magnetoresistive device hasbeen conventionally known. A typical magnetoresistive device provides apair of gap layers between a pair of shield layers, and amagnetoresistive film between the pair of gap layers. The shield layersare formed through electroplating by forming a plating base layerthrough sputtering, sinking it into the electrolyte, and flowing thecurrent through the plating base layer.

Prior art include, for example, Japanese Patent Application, PublicationNo. (“JP”) 5-73842.

The improved magnetic characteristics of the shield layers that shieldthe external magnetic field and one reflux magnetic domains shown inFIG. 7 are preferable in order to realize a highly sensitive read head.The parallel magnetic domains 2 a and 2 b in the longitudinal directionshould be parallel and antiparallel to the predetermined direction. Whenit inclines to the predetermined direction, the abnormal magnetic domainoccurs and deteriorates the magnetic characteristic.

When the magnetic head becomes smaller and the shield layer becomesthinner, a ratio of the plating base layer in the shield layer increasesand the magnetic characteristic or magnetic anisotropy in the platingbase layer greatly affects the magnetic characteristic of the magnetichead. On the other hand, JP 5-73842 improves the magnetic characteristicby executing the shield-layer forming step in the magnetic field (seeparagraph no. 0014). In addition, this reference also proposes the heattreatment in the magnetic field after the plating layer is formed, so asto stabilize the magnetic anisotropy. However, JP 5-73842 is silentabout the direction of the magnetic field in the film formation and thedirection of the magnetic field in the heat treatment, and the magneticdomains 2 a and 2 b do not become parallel or antiparallel to thepredetermined direction.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a method of manufacturing a highlysensitive magnetic head device having a good shield characteristic.

A method according to one aspect of the present invention formanufacturing a magnetic head device that includes a soft magnetic layerincludes the steps of forming a plating base layer in the soft magneticlayer through sputtering, and applying, during the forming step, amagnetic field in a direction parallel to an orientation fringe of awafer in which the magnetic head device is formed. The plating baselayer having superior magnetic anisotropy can be formed when themagnetic field is applied parallel to the orientation fringe. When thesoft magnetic layer is a shield layer that shields the external magneticfield, the shield layer restrains scattering of the magneticcharacteristic for each product, and has high stability to the heat andexternal magnetic field.

The method may further include the steps of forming the soft magneticlayer using the plating base layer through electroplating, and applyingthe magnetic field in the direction during the soft magnetic fieldforming step. Thereby, the plating layer having superior magneticanisotropy can be formed. Preferably, the method includes the step ofheat-treating the wafer in the magnetic field having the same directionas the direction. The deterioration of the magnetic characteristic dueto the heat treatment can be prevented when the subsequent heattreatment maintains the magnetic field having the same direction as thatof the film formation.

The method preferably further includes the step of applying the magneticfield to the wafer in a direction different from the direction at a roomtemperature, followed by the heat-treating step. The heat-treating stepin the magnetic field provides a recovery from the deterioration of themagnetic characteristic due to the magnetic-field applying step at theroom temperature. In that case, the heat-treating step may be performedat least once whenever the step of applying the magnetic field at theroom temperature is performed plural times.

The method preferably includes the step of heat-treating the wafer in anonmagnetic field, followed by the heat-treating step in the magneticfield. The heat-treating step in the magnetic field can provide arecovery from the deterioration of the magnetic characteristic due tothe heat-treating step in the nonmagnetic field. In that case, theheat-treating step in the magnetic field may be performed at least oncewhenever the heat-treating step in the nonmagnetic field is performedplural times. In addition, the heat-treating step in the magnetic fieldhas a temperature higher than that of the heat-treating step in thenonmagnetic field. Thereby, this configuration provides a recovery fromthe deterioration of the magnetic characteristic due to the heattreatment in the nonmagnetic field. The magnetic head device is, forexample, a composite head device that includes a write head device and aread head device.

Other objects and further features of the present invention will becomereadily apparent from the following description of preferred embodimentswith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an enlarged sectional view showing a structure of a magnetichead device, and FIG. 1B is an enlarged sectional view showing astructure of another magnetic head device.

FIG. 2 is a flowchart for explaining a method for manufacturing amagnetic head device according to one embodiment of the presentinvention.

FIG. 3 is a plane view for explaining a magnetic field applyingdirection.

FIG. 4 is a flowchart as a variation of FIG. 2.

FIG. 5A is a table showing a magnetic domain state of a magnetic headdevice manufactured by the manufacturing method of this embodiment. FIG.5B is a graph of FIG. 5A.

FIG. 6A is a table showing a magnetic domain state of a magnetic headdevice manufactured by the conventional manufacturing method. FIG. 6B isa graph of FIG. 6A.

FIG. 7 is a schematic plane view of a reflux magnetic domain.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the accompanying drawings, a magnetic head device usedfor the HDD. The magnetic head device is a magnetoresistive/inductivecomposite head including an inductive head device for writing binaryinformation into the magnetic disc using a magnetic field induced by aconductive coil pattern (not shown), and a magnetoresistive (“MR”hereinafter) head device for reading the resistance as binaryinformation that varies according to a magnetic field generated by themagnetic disc.

The MR head device is applicable to both a type shown in FIG. 1A inwhich the sense current flows parallel to the lamination surfaces of theMR film, and a type shown in FIG. 1B in which the sense current flowsperpendicular to the lamination surfaces of the MR film.

The inductive head device 130 is commonly used for both FIGS. 1A and 1B.The inductive head device 130 includes a nonmagnetic gap layer 132, anupper magnetic pole layer 134, an insulating film 136 made of an Al₂O₃film, and an upper shield-upper electrode layer 139. As discussed later,the upper shield-upper electrode layer 139 also constitutes part of theMR head device 140.

The nonmagnetic gap layer 132 spreads over a surface of the uppershield-upper electrode layer 139, which will be described later, and ismade, for example, of Al₂O₃. The upper magnetic pole layer 134 faces theupper shield-upper electrode layer 139 with respect to the nonmagneticgap layer 132, and is made, for example, of NiFe. The insulating film136 extends over a surface of the nonmagnetic gap layer 132, covers theupper magnetic pole layer 134, and forms the head-device built-in film123. The upper magnetic pole layer 134 and upper shield-upper electrodelayer 139 cooperatively form a magnetic core in the inductive write headdevice 130. A lower magnetic pole layer in the inductive write headdevice 130 serves as the upper shield-upper electrode layer 139 in theMR head device 140. As the conductive coil pattern induces a magneticfield, a magnetic-flux flows between the upper magnetic pole layer 134and upper shield-upper electrode layer 139 leaks from the floatationsurface due to acts of the non-magnetic gap layer 132. The leakingmagnetic-flux flow forms a signal magnetic field (or gap magneticfield).

The MR head device 140 shown in FIG. 1A includes the upper shield layer139, a lower shield layer 142, an upper gap layer 144, a lower gap layer146, a spin-valve film 150, and a lead terminal part 160.

The shield layers 139 and 142 are made, for example, of NiFe. The gaplayers 144 and 146 are made of an insulating material, such as Al₂O₃.139 a and 142 a denote plating base layers in the shield layers 139 and142. Plating layers are formed on the plating base layers 139 a and 142a and become the shield layers 139 and 142. The plating layer is formedby forming the plating base layer through sputtering, sinking theplating base layer in the electrolyte, and flowing the current throughthe plating base layer.

The spin-valve film 150 includes a free ferromagnetic layer 152, anonmagnetic intermediate layer 154, a pinned magnetic layer 156, and anexchange-coupling layer 158, forming a GMR sensor. The spin-valve film150 may have any types including a top-type spin-valve structure, abottom-type spin-valve structure, and a dual spin valve structure.

The lead terminal part 160 has a hard bias layer 162 that generates abias magnetic field, and a terminal layer 166 that applies the sensecurrent and defines the device width WE. Thus, the MR head device 140shown in FIG. 1A is a CIP-GMR device having a CIP structure that appliesthe sense current parallel to the laminated surfaces of the spin-valvefilm 150 or perpendicular to the lamination direction. The hard biaslayer 162 has a primary coat layer 163 made, for example, of Cr, CrTialloy, and TiW alloy, and a hard ferromagnetic layer 164 made, forexample, of such a magnetic material as CoPt alloy and CoCrPt alloy. Theterminal layer 166 includes a primary coat layer 167 made of such anonmagnetic layer as Ta, an electrode layer 167 made of gold, and a caplayer 169 made of Ta.

The MR head device 140A shown in FIG. 1B includes the upper shield layer139, a lower shield layer 142, an upper gap layer 144, a lower gap layer146, a MR film 150A, and a pair of hard bias films 160A arranged at bothsides of the MR film 150A.

The MR film 150A is, for example, a TMR film, which includes, in orderfrom the bottom in FIG. 1B, a free ferromagnetic layer 152A, anonmagnetic insulating layer 154A, a pinned magnetic layer 156A, and anantiferromagnetic layer 158A. The TMR film has a ferromagnetic tunnelingjunction configured to hold the insulating layer 154 between the twoferromagnetic layers, and uses a tunneling phenomenon in which theelectrons in the minus side ferromagnetic layer pass through theinsulating layer to the plus side ferromagnetic layer, when the voltageis applied between the two ferromagnetic layers. The insulating layer154A uses, for example, an Al₂O₃ film.

The MR film 150A may be a spin-valve film. In that case, the MR deviceis a CPP-GMR device, and includes, in order from the bottom shown inFIG. 1B, a free layer 152A, a nonmagnetic intermediate layer 154A, apinned magnetic layer 156A, and an exchange-coupling (antiferromagnetic)layer 158A.

The hard bias film 160A generates a bias magnetic field that restrainsnoises. The hard bias film 160A is made, for example, of such a magneticmaterial as CoPt alloy and CoCrPt alloy.

Referring to now to FIGS. 2 and 3, a description will be given of themagnetic head device. Here, FIG. 2 is a flowchart for explaining themethod of manufacturing the magnetic head device, and a manufacture ofthe upper shield layer 139 and subsequent layers will be mainlydescribed. However, the manufacturing method of this embodiment isapplicable to the other soft magnetic layer, such as the terminal layerusing the plating base layer. First, the plating base layer is made ofNiFe through sputtering (step 1002). In that case, as shown in FIG. 3,during sputtering, a magnetic filed is applied in a direction parallelto the orientation fringe OF of a wafer W in which the magnetic headdevices are formed. The magnetic field is applied through a magneticholder that combines a holder that holds the wafer W with a magnet. Thisinventor has discovered that the plating base layer has superiormagnetic anisotropy by applying the magnetic field parallel to theorientation fringe as in the working example, which will be describedlater. Thereby, the shield layers 139 and 142 restrain scattering of themagnetic characteristic for each product, and have high stability to theheat and external magnetic field.

Next, the shield layer is formed through electroplating while a magneticfield is applied in a direction parallel to the orientation fringe OFshown in FIG. 3 (step 1004). Thereby, the plating layer having magneticanisotropy can be formed. Next, the magnetic field is applied at theroom temperature to the wafer W in a direction perpendicular to theorientation fringe OF (ρ-H) (step 1006). The step 1006 is a magneticcharacteristic test, and applies the magnetic field in the directionperpendicular to the original direction. Thereafter, the wafer W ismagnetized by applying the magnetic field in the direction parallel tothe orientation fringe OF (step 1008). Thereafter, in order to confirmthe magnetic characteristic, the wafer W is magnetized while themagnetic field is applied in a direction perpendicular to theorientation fringe OF (step 1010). Thereafter, the wafer W isheat-treated while the magnetic field is applied in the directionparallel to the orientation fringe OF (step 1012).

Next, resist coating, the alignment, and the development follow (step1014). Thereafter, the wafer W is heat-treated in the magnetic field(hard bake) (step 1016). Thereafter, sputtering, the resist coating, thealignment, and the development follow (step 1018), and then the wafer Wis heat-treated while the magnetic field is applied in the directionparallel to the orientation fringe OF (hard bake) (step 1020). Next,sputtering, the resist coat, the alignment, and the development follow(step 1022), and then the wafer W is heat-treated while the magneticfield is applied in the direction parallel to the orientation fringe OF(hard bake) (step 1024).

Next, resist coating, the alignment, and the development follow (step1026), and then the wafer W is heat-treated while the magnetic field isapplied in the direction parallel to the orientation fringe OF (hardbake) (step 1028). Next, the resist is coated (step 1030). Next, themagnetic field is applied at the room temperature to the wafer W in adirection perpendicular to the orientation fringe OF (ρ-H) for themagnetic characteristic test (step 1032). Thereafter, the wafer W isheat-treated while the magnetic field is applied in the directionparallel to the orientation fringe OF (step 1034). Thereafter, sortingand shipping follow (step 1036).

Steps 1006, 1010 and 1032 are the steps of applying the magnetic fieldat the room temperature to the wafer W in a direction different from themagnetic-field direction in the sputtering step, and have a fear for adeterioration of the shield characteristic. Subsequent to the step 1014is the film formation step of each layer in the inductive head device130. The steps 1012 and 1034 are the newly added steps. The steps 1016,1020, 1024, and 1028 are the heat treatment steps that are performed inthe magnetic field, whereas these steps have been conducted in thenonmagnetic field having a fear for a deterioration of the shieldcharacteristic.

Thus, this embodiment has the heat treatment steps (i.e., the steps1012, 1016, 1020, 1024, 1028, and 1034) that are performed for the waferW in the magnetic field having the same direction as the magnetic fielddirection in the sputtering step 1002. The heat treatment at that timeis preferably performed at the temperature as high as or higher than thenormal heat temperature, such as 220° C. The “normal heat temperature”is the temperature of the above hard bake which has been conducted inthe nonmagnetic field. The hard bake needs that temperature, becauseheating facilitates the magnetic-domain control. The heat treatmentwhich has been conducted in the nonmagnetic field is performed in themagnetic field whose direction accords with the orientation fringe OF ofthe wafer W, and the deterioration of the magnetic characteristic of theshield layer can be prevented.

In addition, this embodiment provides the heat treatment step 1012 inthe magnetic field once after the magnetic-field applying steps 1006 and1010 at the room temperature are performed, but the step 1012 may beperformed once for each of the magnetic-field applying steps 1006 and1010 at the room temperature. Moreover, this embodiment provides theheat treatment steps 1012 and 1034 in the magnetic field for themagnetic-field applying steps 1006, 1010, and 1032 at the roomtemperature, but may provide only the heat treatment step 1034 in themagnetic field. In other words, the heat treatment step in the magneticfield may be provided at least once for plural magnetic-field applyingsteps at the room temperature. In that case, the magnetic characteristiccan be recovered from the deterioration by making the temperature higherthan the normal heat treatment temperature or making a time periodlonger than the normal heat treatment time period.

Referring now to FIG. 4, a description will be given of a variation ofthe manufacturing method of FIG. 2. Here, FIG. 4 is a flowchart of thevariation of the manufacturing method shown in FIG. 2. Those steps inFIG. 4, which are the corresponding steps in FIG. 2, are designated bythe same reference numerals, and a description thereof will be omitted.

This embodiment replaces the steps 1016, 1020, 1024, and 1028 shown inFIG. 2 with the conventional heat treatment (hard bake) steps in thenonmagnetic field (i.e., the steps 1040, 1044, 1048, and 1052), and addthe heat treatment steps in the magnetic field (i.e., the steps 1042,1046, 1050, and 1054). Preferably, the heat treatment is performed atthe temperature as high as or higher than the normal heat treatmenttemperature, such as 220° C. The “normal heat treatment temperature” isthe temperature of the above heat treatment steps in the nonmagneticfield (i.e., the steps 1040, 1044, 1048, and 1052) in this embodiment.This is because the temperature as high as or higher than thetemperature is effective to the recovery from the deterioration of themagnetic characteristic due to the heat treatment in the nonmagneticfield. The magnetic field direction of the heat treatment in themagnetic field corresponding to the orientation fringe OF of the wafer Wwould prevent the deterioration of the magnetic characteristic of theshield layer due to the heat treatment.

In addition, this embodiment provides the heat treatment step in themagnetic field once after the heat treatment step in the nonmagneticfield, but it is sufficient to provide the heat treatment step in themagnetic field once after plural heat treatment steps in the nonmagneticfield. Therefore, only the step 1054 may be provided. In this case, asdescribed above, the magnetic characteristic can be recovered from thedeterioration by making the temperature higher than the normal heattreatment temperature or making the heat treatment time period longerthan the normal heat treatment temperature time period.

WORKING EXAMPLE

According to the manufacturing method of this embodiment, two magneticdomains (ideal magnetic domains), three magnetic domains, and abnormalmagnetic domains are observed after the plating base layer is sputteredwhile the magnetic field is applied parallel to the orientation fringeOF, after the heat treatment in the magnetic field, after the heattreatment in the nonmagnetic field, and after the reheat treatment inthe magnetic field. In other words, this observation corresponds to anobservation after each of the steps 1002, 1012, 1040, and 1042 shown inFIG. 6B. In general, {100%−(a ratio (%) of the two magnetic domains)+(aratio (%) of the three magnetic domains)}=(a ratio (%) of the abnormalmagnetic domains) is met, but four or more magnetic domains can exist.The two magnetic domains mean that there are two magnetic domains 2 aand 2 b parallel to the longitudinal direction, as shown in FIG. 7, inthe reflux magnetic domain. On the other hand, the three magneticdomains mean that there are three magnetic domains. The abnormalmagnetic domains mean that magnetic domains 2 a and 2 b parallel to thelongitudinal direction incline to the orientation fringe OF. FIGS. 5Aand 5B show the result. It is understood that the ratio of the abnormalmagnetic domains is maintained 0% at each stage. It is also understoodthat the ideal, two magnetic domains is improved by the heat treatmentin the magnetic field, and deteriorated in the heat treatment in thenonmagnetic field, but improved up to 97% in the reheat treatment in themagnetic field.

COMPARATIVE EXAMPLE

According to the conventional manufacturing method, two magnetic domains(ideal magnetic domains), three magnetic domains, and abnormal magneticdomains are observed after sputtering, after the heat treatment in themagnetic field, after the heat treatment in the nonmagnetic field, andafter the reheat treatment in the magnetic field. In the comparativeexample, the plating base layer is sputtered in the nonmagnetic field,and the heat treatment in the magnetic field, and the reheat treatmentin the magnetic field are added, which have never existed originally.FIGS. 6A and 6B show the result. It is understood that the ratios of theabnormal magnetic domain are 100%, 58%, 44%, and 61% at respectivestages. In other words, it is understood that when the plating baselayer is sputtered in the nonmagnetic field, the abnormal magneticdomains always remains even after it undergoes the heat treatment in themagnetic field.

Further, the present invention is not limited to these preferredembodiments, and various variations and modifications may be madewithout departing from the scope of the present invention.

Thus, the present invention can provide a method of manufacturing ahighly sensitive magnetic head device having a good shieldcharacteristic.

1. A method for manufacturing a magnetic head device that includes asoft magnetic layer, said method comprising the steps of: forming aplating base layer in the soft magnetic layer through sputtering; andapplying, during said forming step, a magnetic field in a directionparallel to an orientation fringe of a wafer in which the magnetic headdevice is formed.
 2. A method according to claim 1, wherein the softmagnetic layer is a shield layer that shields an external magneticfield.
 3. A method according to claim 1, further comprising the stepsof: forming the soft magnetic layer using the plating base layer throughelectroplating; and applying the magnetic field in the direction duringsaid soft magnetic field forming step.
 4. A method according to claim 1,further comprising the step of heat-treating the wafer in the magneticfield having the same direction as the direction.
 5. A method accordingto claim 4, further comprising the step of applying the magnetic fieldto the wafer in a direction different from the direction at a roomtemperature, followed by said heat-treating step.
 6. A method accordingto claim 5, wherein said heat-treating step is performed at least oncewhenever the step of applying the magnetic field at the room temperatureis performed plural times.
 7. A method according to claim 4, furthercomprising the step of heat-treating the wafer in a nonmagnetic field,followed by said heat-treating step in the magnetic field.
 8. A methodaccording to claim 7, wherein said heat-treating step in the magneticfield is performed at least once whenever said heat-treating step in thenonmagnetic field is performed plural times.
 9. A method according toclaim 7, wherein said heat-treating step in the magnetic field has atemperature higher than that of said heat-treating step in thenonmagnetic field.
 10. A method according to claim 1, wherein themagnetic head device is a composite head device that includes a writehead device and a read head device.